Im set in all my jazz basses with my favourite strings: Rotosound solo bass 40-60-80-100, they are nice ground/pressurewounds and I love the tone and feeling now Im about to get a shortscale bass (30) and I would like to use these strings but in order to get a higher tension feeling in the shortscale Im aware I MUST INCREASE THE STRINGS GAUGE My ideal situation would be to have the same string tension in both the 34 bass and the 30 bass Im willing to increase string gauge but how much more gauge would I need? I could get the same stings with 45, 65, 85, 105 for the 30 bass, but will this be enough to achieve the same kind of tension that Im getting with the 40-60-80-100 in a 34 bass? Will strings be balanced? I mean, how does string gauge translate to tension?
For the most part, higher gauge = higher tension. However, this is not a universal truth. Most manufacturers do not publish unit weight specs, and so tensions can only be estimated based on Circle K or D'Addario specs as they are the only two companies that publish useful specs. (TI actually does too, but their string gauge selection is limited and they use different-enough winding techniques that I don't think it's useful.) By my estimates, a 4" drop in scale translates to an increase of about 0.015". So your 100-40 set would need to be at 115-55 to match tension. The other option is just to look for stiffer strings, or just get used to the lower tension of a shortscale.
This explains everything http://www.daddario.com/upload/tension_chart_13934.pdf There are tension charts for short scale 30" and long scale 34" so you can compare. Also, a shorter scale creates an illusion of more tension so you can use a slightly lower actual tension.
Higher gauge doesn't always mean higher tension. I hear that TIs are low tension compared to, say rotos of the same gauge, which might as well be solid metal rod.
